Structure Characteristics Research Of Orthotropic Deck Flat Steel Box Girders

The Severn Bridge is the first bridge in the world to be built with a orthotropic deck steel box girder of aerodynamic cross-section and inclined hangers. Using this section mostly idea to reduce aerodynamic instability. Simultaneity, orthotropic deck provide an excellent solution for any large-scale structures where weight is an issue. So, this type of construction was used later for a bridge over the Bosporus at Istanbul, the Littebelt bridge in Denmark, and the Humber bridge in Northern England. In fact, orthotropic deck steel box girders are suited any bridge where weight or hight of gieder is an important issue.Box girders are susceptible to cross sectional distortion under eccentric loading condition.It is important to analysis the ratio of the distortional warping normal stress to the bending normal stress. Steel box girder is a welded, all-steel superstructure, weld residual stress strongly affect its fatigue life. Another most challenge to design for fatigue is the connection detail between the longitudinal ribs and the diaphragm plate.Research of performance characteristics of this structure with finite element analysis is presented in this thesis. Three level finite element models of a real steel orthotropic deck flat box girder are presented in this thesis.1. The 3D shell model of the steel orthotropic deck box girder block includes deck plate, bottom plate, ribs, diaphragm and web. This model can consider the girder bending and torsion action as well as warping, shear lag, and the interaction of structural element.2. A second level model can be developed for considering weld residual stress of U rib to deck plate and made up of 3D block element, it's a thermal-structure sequentially couple field analysis. The stress spectra obtained from this model can be used to study ultimate strength and fatigue strength of U rib orthotropic deck, and to predict the life of this box girder.3. The third model be mainly made up for considering geometry detail of orthotropic deck. Stress concentration nearly cutout and stress of deck plate, U ribs and its diaphragm plate are simulated. All these studies aim to deeply understand structure characters of steel orthotropic deck box girder, the results can be used to aid design, fabrication, erection and health monitor of those girders.